An electrophoretic display (EPD) is a non-emissive device based on the electrophoresis phenomenon of charged pigment particles suspended in a solvent. The display usually comprises two plates with electrodes placed opposing each other. One of the electrodes is usually transparent. A suspension composed of a colored solvent and charged pigment particles is enclosed between the two plates. When a voltage difference is imposed between the two electrodes, the pigment particles migrate to one side or the other, according to the polarity of the voltage difference. As a result, either the color of the pigment particles or the color of the solvent may be seen at the viewing side. An EPD may be driven by a uni-polar or bi-polar approach.
However, the driving methods currently available pose a restriction on the number of grayscale outputs. This is due to the fact that display driver ICs and display controllers are limited in speed on the minimum pulse length that a waveform can have. While current active matrix display architectures utilize ICs that can generate pulse lengths down to 8 msec leading to electrophoretic displays which have shortened response time, even below 150 msec, the grayscale resolution seems to diminish due to the incapability of the system to generate shorter pulse lengths.
In addition, the driving methods currently available are not sufficient for driving a color display device.